1. Field of the Invention
This invention relates generally to high voltage power supply lines, and more specifically to tools for use in connection with high voltage lines and methods for using those tools.
2. Brief Description of the Prior Art
At voltages less than about 7.6 kilovolts, a worker wearing appropriate protective gear can handle energized lines directly. With lines at higher voltages, however, a different approach must be employed to guard against high voltage hazards. Frequently, workers who manipulate lines carrying such higher voltages use tools which are mounted at the end of "hot sticks". These are insulated poles extending about eight feet or more in length. Hot stick-mounted tools are adapted to a variety of tasks. For example, U.S. Pat. No. 4,326,316 discloses a hot stick-mounted rotary brush for cleaning aerial conductors; U.S. Pat. No. 4,132,441 relates to a hot stick-mounted head for removing fuse holders; and U.S. Pat. No. 3,866,965 discloses an attachment for facilitating manipulation of overhead wires with a hot stick. Similarly, U.S. Pat. Nos. 4,079,978 and 3,868,136 disclose improved hot sticks.
In working with high voltage power supply systems, it is frequently required that a section of line be deenergized. This is often accomplished by installing a string of insulator discs in an energized line. Typically, a string of discs having a pair of rigid extension bars extending from either end of the insulator string is used, the extension bars having multibolt cable clamps at their free ends. To install the insulator string, a hot stick equipped with a clamp adapted to securely engage the disc string proximate the center of the string is used. The disc string is clamped using the tool and held in the vicinity of the energized line by one worker, while two others secure each of the cable clamps to the energized line and subsequently sever the energized line in between the cable clamps using other hot stick-mounted tools. After both cable clamps have been secured to the energized line, the insulator clamp can be opened, since the insulator sting is then being suspended from the energized line by the cable clamps. This method of installing insulator strings disadvantageously requires three workers while the cable clamps are being fastened.